DS-4107 Retrieve and model metadata as a map

src/app/+item-page/edit-item-page/modify-item-overview/modify-item-overview.component.html

@@ -7,10 +7,12 @@
   </tr>
   </thead>
   <tbody>
-  <tr *ngFor="let metadatum of metadata" class="metadata-row">
+  <ng-container *ngFor="let entry of metadata | keyvalue">
-    <td>{{metadatum.key}}</td>
+    <tr *ngFor="let value of entry.value" class="metadata-row">
-    <td>{{metadatum.value}}</td>
+      <td>{{entry.key}}</td>
-    <td>{{metadatum.language}}</td>
+      <td>{{value.value}}</td>
-  </tr>
+      <td>{{value.language}}</td>
+    </tr>
+  </ng-container>
   </tbody>
 </table>

src/app/+item-page/edit-item-page/modify-item-overview/modify-item-overview.component.ts

@@ -1,6 +1,6 @@
 import {Component, Input, OnInit} from '@angular/core';
 import {Item} from '../../../core/shared/item.model';
-import {Metadatum} from '../../../core/shared/metadatum.model';
+import {MetadataMap} from '../../../core/shared/metadata.interfaces';
 
 @Component({
   selector: 'ds-modify-item-overview',
@@ -12,7 +12,7 @@ import {Metadatum} from '../../../core/shared/metadatum.model';
 export class ModifyItemOverviewComponent implements OnInit {
 
   @Input() item: Item;
-  metadata: Metadatum[];
+  metadata: MetadataMap;
 
   ngOnInit(): void {
     this.metadata = this.item.metadata;

src/app/+item-page/field-components/metadata-uri-values/metadata-uri-values.component.html

@@ -1,5 +1,5 @@
 <ds-metadata-field-wrapper [label]="label | translate">
-    <a *ngFor="let metadatum of values; let last=last;" [href]="metadatum.value">
+    <a *ngFor="let value of values; let last=last;" [href]="value.value">
-       {{ linktext || metadatum.value }}<span *ngIf="!last" [innerHTML]="separator"></span>
+       {{ linktext || value.value }}<span *ngIf="!last" [innerHTML]="separator"></span>
     </a>
 </ds-metadata-field-wrapper>

src/app/+item-page/field-components/metadata-uri-values/metadata-uri-values.component.ts

@@ -1,6 +1,7 @@
 import { Component, Input } from '@angular/core';
 
 import { MetadataValuesComponent } from '../metadata-values/metadata-values.component';
+import { MetadataValue } from '../../../core/shared/metadata.interfaces';
 
 /**
  * This component renders the configured 'values' into the ds-metadata-field-wrapper component as a link.
@@ -18,7 +19,7 @@ export class MetadataUriValuesComponent extends MetadataValuesComponent {
 
   @Input() linktext: any;
 
-  @Input() values: any;
+  @Input() values: MetadataValue[];
 
   @Input() separator: string;
 

src/app/+item-page/field-components/metadata-values/metadata-values.component.html

@@ -1,5 +1,5 @@
 <ds-metadata-field-wrapper [label]="label | translate">
-    <span *ngFor="let metadatum of values; let last=last;">
+    <span *ngFor="let value of values; let last=last;">
-        {{metadatum.value}}<span *ngIf="!last" [innerHTML]="separator"></span>
+        {{value.value}}<span *ngIf="!last" [innerHTML]="separator"></span>
     </span>
 </ds-metadata-field-wrapper>

src/app/+item-page/field-components/metadata-values/metadata-values.component.ts

@@ -1,5 +1,5 @@
 import { Component, Input } from '@angular/core';
-import { Metadatum } from '../../../core/shared/metadatum.model';
+import { MetadataValue } from '../../../core/shared/metadata.interfaces';
 
 /**
  * This component renders the configured 'values' into the ds-metadata-field-wrapper component.
@@ -12,7 +12,7 @@ import { Metadatum } from '../../../core/shared/metadatum.model';
 })
 export class MetadataValuesComponent {
 
-  @Input() values: Metadatum[];
+  @Input() values: MetadataValue[];
 
   @Input() separator: string;
 

src/app/+item-page/full/field-components/file-section/full-file-section.component.html

@@ -17,7 +17,7 @@
 
 
                 <dt class="col-md-4">{{"item.page.filesection.description" | translate}}</dt>
-                <dd class="col-md-8">{{file.findMetadata("dc.description")}}</dd>
+                <dd class="col-md-8">{{file.firstMetadataValue("dc.description")}}</dd>
             </dl>
         </div>
         <div class="col-2">

src/app/+item-page/full/full-item-page.component.html

@@ -9,11 +9,13 @@
       </div>
       <table class="table table-responsive table-striped">
         <tbody>
-        <tr *ngFor="let metadatum of (metadata$ | async)">
+          <ng-container *ngFor="let entry of (metadata$ | async) | keyvalue">
-          <td>{{metadatum.key}}</td>
+            <tr *ngFor="let value of entry.value">
-          <td>{{metadatum.value}}</td>
+              <td>{{entry.key}}</td>
-          <td>{{metadatum.language}}</td>
+              <td>{{value.value}}</td>
-        </tr>
+              <td>{{value.language}}</td>
+            </tr>
+          </ng-container>
         </tbody>
       </table>
       <ds-item-page-full-file-section [item]="item"></ds-item-page-full-file-section>

src/app/+item-page/full/full-item-page.component.ts

@@ -6,7 +6,7 @@ import { ActivatedRoute } from '@angular/router';
 import { Observable } from 'rxjs';
 
 import { ItemPageComponent } from '../simple/item-page.component';
-import { Metadatum } from '../../core/shared/metadatum.model';
+import { MetadataMap } from '../../core/shared/metadata.interfaces';
 import { ItemDataService } from '../../core/data/item-data.service';
 
 import { RemoteData } from '../../core/data/remote-data';
@@ -34,7 +34,7 @@ export class FullItemPageComponent extends ItemPageComponent implements OnInit {
 
   itemRD$: Observable<RemoteData<Item>>;
 
-  metadata$: Observable<Metadatum[]>;
+  metadata$: Observable<MetadataMap>;
 
   constructor(route: ActivatedRoute, items: ItemDataService, metadataService: MetadataService) {
     super(route, items, metadataService);

src/app/+item-page/simple/field-components/specific-field/item-page-specific-field.component.html

@@ -1,3 +1,3 @@
 <div class="item-page-specific-field">
-  <ds-metadata-values [values]="item?.filterMetadata(fields)" [separator]="separator" [label]="label"></ds-metadata-values>
+  <ds-metadata-values [values]="item?.allMetadata(fields)" [separator]="separator" [label]="label"></ds-metadata-values>
 </div>

src/app/+item-page/simple/field-components/specific-field/title/item-page-title-field.component.html

@@ -1,3 +1,3 @@
 <h2 class="item-page-title-field">
-  <ds-metadata-values [values]="item?.filterMetadata(fields)"></ds-metadata-values>
+  <ds-metadata-values [values]="item?.allMetadata(fields)"></ds-metadata-values>
 </h2>

src/app/+item-page/simple/field-components/specific-field/uri/item-page-uri-field.component.html

@@ -1,3 +1,3 @@
 <div class="item-page-specific-field">
-  <ds-metadata-uri-values [values]="item?.filterMetadata(fields)" [separator]="separator" [label]="label"></ds-metadata-uri-values>
+  <ds-metadata-uri-values [values]="item?.allMetadata(fields)" [separator]="separator" [label]="label"></ds-metadata-uri-values>
 </div>

src/app/+search-page/normalized-search-result.model.ts

@@ -1,5 +1,5 @@
 import { autoserialize } from 'cerialize';
-import { Metadatum } from '../core/shared/metadatum.model';
+import { MetadataMap } from '../core/shared/metadata.interfaces';
 import { ListableObject } from '../shared/object-collection/shared/listable-object.model';
 
 /**
@@ -16,6 +16,6 @@ export class NormalizedSearchResult implements ListableObject {
    * The metadata that was used to find this item, hithighlighted
    */
   @autoserialize
-  hitHighlights: Metadatum[];
+  hitHighlights: MetadataMap;
 
 }

src/app/+search-page/search-result.model.ts

@@ -1,5 +1,5 @@
 import { DSpaceObject } from '../core/shared/dspace-object.model';
-import { Metadatum } from '../core/shared/metadatum.model';
+import { MetadataMap } from '../core/shared/metadata.interfaces';
 import { ListableObject } from '../shared/object-collection/shared/listable-object.model';
 
 /**
@@ -14,6 +14,6 @@ export class SearchResult<T extends DSpaceObject> implements ListableObject {
   /**
    * The metadata that was used to find this item, hithighlighted
    */
-  hitHighlights: Metadatum[];
+  hitHighlights: MetadataMap;
 
 }

src/app/core/browse/browse.service.ts

@@ -38,8 +38,8 @@ import { DSpaceObject } from '../shared/dspace-object.model';
 export class BrowseService {
   protected linkPath = 'browses';
 
-  private static toSearchKeyArray(metadatumKey: string): string[] {
+  private static toSearchKeyArray(metadataKey: string): string[] {
-    const keyParts = metadatumKey.split('.');
+    const keyParts = metadataKey.split('.');
     const searchFor = [];
     searchFor.push('*');
     for (let i = 0; i < keyParts.length - 1; i++) {
@@ -47,7 +47,7 @@ export class BrowseService {
       const nextPart = [...prevParts, '*'].join('.');
       searchFor.push(nextPart);
     }
-    searchFor.push(metadatumKey);
+    searchFor.push(metadataKey);
     return searchFor;
   }
 
@@ -179,8 +179,8 @@ export class BrowseService {
     return this.rdb.toRemoteDataObservable(requestEntry$, payload$);
   }
 
-  getBrowseURLFor(metadatumKey: string, linkPath: string): Observable<string> {
+  getBrowseURLFor(metadataKey: string, linkPath: string): Observable<string> {
-    const searchKeyArray = BrowseService.toSearchKeyArray(metadatumKey);
+    const searchKeyArray = BrowseService.toSearchKeyArray(metadataKey);
     return this.getBrowseDefinitions().pipe(
       getRemoteDataPayload(),
       map((browseDefinitions: BrowseDefinition[]) => browseDefinitions
@@ -191,7 +191,7 @@ export class BrowseService {
       ),
       map((def: BrowseDefinition) => {
         if (isEmpty(def) || isEmpty(def._links) || isEmpty(def._links[linkPath])) {
-          throw new Error(`A browse endpoint for ${linkPath} on ${metadatumKey} isn't configured`);
+          throw new Error(`A browse endpoint for ${linkPath} on ${metadataKey} isn't configured`);
         } else {
           return def._links[linkPath];
         }

src/app/core/cache/models/normalized-dspace-object.model.ts

@@ -1,7 +1,6 @@
 import { autoserialize, autoserializeAs, deserialize, serialize } from 'cerialize';
 import { DSpaceObject } from '../../shared/dspace-object.model';
-
+import { MetadataMap } from '../../shared/metadata.interfaces';
-import { Metadatum } from '../../shared/metadatum.model';
 import { ResourceType } from '../../shared/resource-type';
 import { mapsTo } from '../builders/build-decorators';
 import { NormalizedObject } from './normalized-object.model';
@@ -46,10 +45,10 @@ export class NormalizedDSpaceObject extends NormalizedObject {
   type: ResourceType;
 
   /**
-   * An array containing all metadata of this DSpaceObject
+   * All metadata of this DSpaceObject
    */
-  @autoserializeAs(Metadatum)
+  @autoserialize
-  metadata: Metadatum[];
+  metadata: MetadataMap;
 
   /**
    * An array of DSpaceObjects that are direct parents of this DSpaceObject

src/app/core/data/search-response-parsing.service.ts

@@ -7,7 +7,7 @@ import { DSpaceRESTV2Response } from '../dspace-rest-v2/dspace-rest-v2-response.
 import { DSpaceRESTv2Serializer } from '../dspace-rest-v2/dspace-rest-v2.serializer';
 import { hasValue } from '../../shared/empty.util';
 import { SearchQueryResponse } from '../../+search-page/search-service/search-query-response.model';
-import { Metadatum } from '../shared/metadatum.model';
+import { MetadataMap, MetadataValue } from '../shared/metadata.interfaces';
 
 @Injectable()
 export class SearchResponseParsingService implements ResponseParsingService {
@@ -16,17 +16,17 @@ export class SearchResponseParsingService implements ResponseParsingService {
 
   parse(request: RestRequest, data: DSpaceRESTV2Response): RestResponse {
     const payload = data.payload._embedded.searchResult;
-    const hitHighlights = payload._embedded.objects
+    const hitHighlights: MetadataMap[] = payload._embedded.objects
       .map((object) => object.hitHighlights)
       .map((hhObject) => {
+        const mdMap: MetadataMap = {};
         if (hhObject) {
-          return Object.keys(hhObject).map((key) => Object.assign(new Metadatum(), {
+          for (const key of Object.keys(hhObject)) {
-            key: key,
+            const value: MetadataValue = { value: hhObject[key].join('...'), language: null };
-            value: hhObject[key].join('...')
+            mdMap[key] = [ value ];
-          }))
+          }
-        } else {
-          return [];
         }
+        return mdMap;
       });
 
     const dsoSelfLinks = payload._embedded.objects

src/app/core/dspace-rest-v2/dspace-rest-v2.service.ts

@@ -91,9 +91,9 @@ export class DSpaceRESTv2Service {
     const form: FormData = new FormData();
     form.append('name', dso.name);
     if (dso.metadata) {
-      for (const i of Object.keys(dso.metadata)) {
+      for (const key of Object.keys(dso.metadata)) {
-        if (isNotEmpty(dso.metadata[i].value)) {
+        for (const value of dso.allMetadataValues(key)) {
-          form.append(dso.metadata[i].key, dso.metadata[i].value);
+          form.append(key, value);
         }
       }
     }

src/app/core/metadata/metadata.service.ts

@@ -294,6 +294,10 @@ export class MetadataService {
     }
   }
 
+  private hasType(value: string): boolean {
+    return this.currentObject.value.hasMetadata('dc.type', { value: value, ignoreCase: true });
+  }
+
   /**
    * Returns true if this._item is a dissertation
    *
@@ -301,14 +305,7 @@ export class MetadataService {
    *      true if this._item has a dc.type equal to 'Thesis'
    */
   private isDissertation(): boolean {
-    let isDissertation = false;
+    return this.hasType('thesis');
-    for (const metadatum of this.currentObject.value.metadata) {
-      if (metadatum.key === 'dc.type') {
-        isDissertation = metadatum.value.toLowerCase() === 'thesis';
-        break;
-      }
-    }
-    return isDissertation;
   }
 
   /**
@@ -318,40 +315,15 @@ export class MetadataService {
    *      true if this._item has a dc.type equal to 'Technical Report'
    */
   private isTechReport(): boolean {
-    let isTechReport = false;
+    return this.hasType('technical report');
-    for (const metadatum of this.currentObject.value.metadata) {
-      if (metadatum.key === 'dc.type') {
-        isTechReport = metadatum.value.toLowerCase() === 'technical report';
-        break;
-      }
-    }
-    return isTechReport;
   }
 
   private getMetaTagValue(key: string): string {
-    let value: string;
+    return this.currentObject.value.firstMetadataValue(key);
-    for (const metadatum of this.currentObject.value.metadata) {
-      if (metadatum.key === key) {
-        value = metadatum.value;
-      }
-    }
-    return value;
   }
 
   private getFirstMetaTagValue(keys: string[]): string {
-    let value: string;
+    return this.currentObject.value.firstMetadataValue(keys);
-    for (const metadatum of this.currentObject.value.metadata) {
-      for (const key of keys) {
-        if (key === metadatum.key) {
-          value = metadatum.value;
-          break;
-        }
-      }
-      if (value !== undefined) {
-        break;
-      }
-    }
-    return value;
   }
 
   private getMetaTagValuesAndCombine(key: string): string {
@@ -359,15 +331,7 @@ export class MetadataService {
   }
 
   private getMetaTagValues(keys: string[]): string[] {
-    const values: string[] = [];
+    return this.currentObject.value.allMetadataValues(keys);
-    for (const metadatum of this.currentObject.value.metadata) {
-      for (const key of keys) {
-        if (key === metadatum.key) {
-          values.push(metadatum.value);
-        }
-      }
-    }
-    return values;
   }
 
   private addMetaTag(property: string, content: string): void {

src/app/core/shared/collection.model.ts

@@ -16,7 +16,7 @@ export class Collection extends DSpaceObject {
    * Corresponds to the metadata field dc.description
    */
   get introductoryText(): string {
-    return this.findMetadata('dc.description');
+    return this.firstMetadataValue('dc.description');
   }
 
   /**
@@ -24,7 +24,7 @@ export class Collection extends DSpaceObject {
    * Corresponds to the metadata field dc.description.abstract
    */
   get shortDescription(): string {
-    return this.findMetadata('dc.description.abstract');
+    return this.firstMetadataValue('dc.description.abstract');
   }
 
   /**
@@ -32,7 +32,7 @@ export class Collection extends DSpaceObject {
    * Corresponds to the metadata field dc.rights
    */
   get copyrightText(): string {
-    return this.findMetadata('dc.rights');
+    return this.firstMetadataValue('dc.rights');
   }
 
   /**
@@ -40,7 +40,7 @@ export class Collection extends DSpaceObject {
    * Corresponds to the metadata field dc.rights.license
    */
   get license(): string {
-    return this.findMetadata('dc.rights.license');
+    return this.firstMetadataValue('dc.rights.license');
   }
 
   /**
@@ -48,7 +48,7 @@ export class Collection extends DSpaceObject {
    * Corresponds to the metadata field dc.description.tableofcontents
    */
   get sidebarText(): string {
-    return this.findMetadata('dc.description.tableofcontents');
+    return this.firstMetadataValue('dc.description.tableofcontents');
   }
 
   /**

src/app/core/shared/community.model.ts

@@ -17,7 +17,7 @@ export class Community extends DSpaceObject {
    * Corresponds to the metadata field dc.description
    */
   get introductoryText(): string {
-    return this.findMetadata('dc.description');
+    return this.firstMetadataValue('dc.description');
   }
 
   /**
@@ -25,7 +25,7 @@ export class Community extends DSpaceObject {
    * Corresponds to the metadata field dc.description.abstract
    */
   get shortDescription(): string {
-    return this.findMetadata('dc.description.abstract');
+    return this.firstMetadataValue('dc.description.abstract');
   }
 
   /**
@@ -33,7 +33,7 @@ export class Community extends DSpaceObject {
    * Corresponds to the metadata field dc.rights
    */
   get copyrightText(): string {
-    return this.findMetadata('dc.rights');
+    return this.firstMetadataValue('dc.rights');
   }
 
   /**
@@ -41,7 +41,7 @@ export class Community extends DSpaceObject {
    * Corresponds to the metadata field dc.description.tableofcontents
    */
   get sidebarText(): string {
-    return this.findMetadata('dc.description.tableofcontents');
+    return this.firstMetadataValue('dc.description.tableofcontents');
   }
 
   /**

src/app/core/shared/dspace-object.model.ts

@@ -1,5 +1,5 @@
-import { Metadatum } from './metadatum.model'
+import { MetadataMap, MetadataValue, MetadataValueFilter } from './metadata.interfaces';
-import { isEmpty, isNotEmpty } from '../../shared/empty.util';
+import { Metadata } from './metadata.model';
 import { CacheableObject } from '../cache/object-cache.reducer';
 import { RemoteData } from '../data/remote-data';
 import { ResourceType } from './resource-type';
@@ -35,14 +35,14 @@ export class DSpaceObject implements CacheableObject, ListableObject {
    * The name for this DSpaceObject
    */
   get name(): string {
-    return this.findMetadata('dc.title');
+    return this.firstMetadataValue('dc.title');
   }
 
   /**
-   * An array containing all metadata of this DSpaceObject
+   * All metadata of this DSpaceObject
    */
   @autoserialize
-  metadata: Metadatum[] = [];
+  metadata: MetadataMap;
 
   /**
    * An array of DSpaceObjects that are direct parents of this DSpaceObject
@@ -54,42 +54,29 @@ export class DSpaceObject implements CacheableObject, ListableObject {
    */
   owner: Observable<RemoteData<DSpaceObject>>;
 
-  /**
+  /** Gets all matching metadata in this DSpaceObject. See `Metadata.all` for more information. */
-   * Find a metadata field by key and language
+  allMetadata(keyOrKeys: string | string[], valueFilter?: MetadataValueFilter): MetadataValue[] {
-   *
+    return Metadata.all(this.metadata, keyOrKeys, valueFilter);
-   * This method returns the value of the first element
-   * in the metadata array that matches the provided
-   * key and language
-   *
-   * @param key
-   * @param language
-   * @return string
-   */
-  findMetadata(key: string, language?: string): string {
-    const metadatum = this.metadata.find((m: Metadatum) => {
-      return m.key === key && (isEmpty(language) || m.language === language)
-    });
-    if (isNotEmpty(metadatum)) {
-      return metadatum.value;
-    } else {
-      return undefined;
-    }
   }
 
-  /**
+  /** Like `allMetadata`, but only returns string values. */
-   * Find metadata by an array of keys
+  allMetadataValues(keyOrKeys: string | string[], valueFilter?: MetadataValueFilter): string[] {
-   *
+    return Metadata.allValues(this.metadata, keyOrKeys, valueFilter);
-   * This method returns the values of the element
+  }
-   * in the metadata array that match the provided
+
-   * key(s)
+  /** Gets the first matching metadata in this DSpaceObject, or `undefined`. */
-   *
+  firstMetadata(keyOrKeys: string | string[], valueFilter?: MetadataValueFilter): MetadataValue {
-   * @param key(s)
+    return Metadata.first(this.metadata, keyOrKeys, valueFilter);
-   * @return Array<Metadatum>
+  }
-   */
+
-  filterMetadata(keys: string[]): Metadatum[] {
+  /** Like `firstMetadata`, but only returns a string value, or `undefined`. */
-    return this.metadata.filter((metadatum: Metadatum) => {
+  firstMetadataValue(keyOrKeys: string | string[], valueFilter?: MetadataValueFilter): string {
-      return keys.some((key) => key === metadatum.key);
+    return Metadata.firstValue(this.metadata, keyOrKeys, valueFilter);
-    });
+  }
+
+  /** Checks for matching metadata in this DSpaceObject. */
+  hasMetadata(keyOrKeys: string | string[], valueFilter?: MetadataValueFilter): boolean {
+    return Metadata.has(this.metadata, keyOrKeys, valueFilter);
   }
 
 }

src/app/core/shared/metadata.interfaces.ts

@@ -0,0 +1,30 @@
+/** A map of metadata keys to an ordered list of MetadataValue objects. */
+export interface MetadataMap {
+  [ key: string ]: MetadataValue[];
+}
+
+/** A single metadata value and its properties. */
+export interface MetadataValue {
+
+  /** The language. */
+  language: string;
+
+  /** The string value. */
+  value: string;
+}
+
+/** Constraints for matching metadata values. */
+export interface MetadataValueFilter {
+
+  /** The language constraint. */
+  language?: string;
+
+  /** The value constraint. */
+  value?: string;
+
+  /** Whether the value constraint should match without regard to case. */
+  ignoreCase?: boolean;
+
+  /** Whether the value constraint should match as a substring. */
+  substring?: boolean;
+}

src/app/core/shared/metadata.model.ts

@@ -0,0 +1,119 @@
+import { isEmpty } from '../../shared/empty.util';
+import { MetadataMap, MetadataValue, MetadataValueFilter } from './metadata.interfaces';
+
+/**
+ * Static utility methods for working with DSpace metadata.
+ */
+export class Metadata {
+
+  /**
+   * Gets all matching metadata.
+   *
+   * @param {MetadataMap|MetadataMap[]} mapOrMaps The source map(s). Values will only be returned from one map --
+   * the first with at least one match.
+   * @param {string|string[]} keyOrKeys The metadata key(s) in scope. Wildcards are supported, so `'*'` will
+   * match all keys, `'dc.date.*'` will match all qualified dc dates, and so on. Exact keys will be evaluated
+   * (and matches returned) in the order they are given in the parameter. When multiple keys match a wildcard,
+   * they are evaluated in the order they are stored in the map (alphanumeric if obtained from the REST api).
+   * If duplicate or overlapping keys are specified, the first one takes precedence. For example, specifying
+   * `['dc.date', 'dc.*', '*']` will cause any `dc.date` values to be evaluated (and returned, if matched)
+   * first, followed by any other `dc` metadata values, followed by any other (non-dc) metadata values.
+   * @param {MetadataValueFilter} filter The value filter to use.
+   * @returns {MetadataValue[]} the matching values or an empty array.
+   */
+  public static all(mapOrMaps: MetadataMap | MetadataMap[], keyOrKeys: string | string[],
+                    filter?: MetadataValueFilter): MetadataValue[] {
+    const mdMaps: MetadataMap[] = mapOrMaps instanceof Array ? mapOrMaps : [ mapOrMaps ];
+    const matches: MetadataValue[] = [];
+    for (const mdMap of mdMaps) {
+      for (const mdKey of Metadata.resolveKeys(mdMap, keyOrKeys)) {
+        const candidates = mdMap[mdKey];
+        if (candidates) {
+          for (const candidate of candidates) {
+            if (Metadata.valueMatches(candidate, filter)) {
+              matches.push(candidate);
+            }
+          }
+        }
+      }
+      if (!isEmpty(matches)) {
+        return matches;
+      }
+    }
+    return matches;
+  }
+
+  /** Like `all`, but only returns string values. */
+  public static allValues(mapOrMaps: MetadataMap | MetadataMap[], keyOrKeys: string | string[],
+                          filter?: MetadataValueFilter): string[] {
+    return Metadata.all(mapOrMaps, keyOrKeys, filter).map((mdValue) => mdValue.value);
+  }
+
+  /** Gets the first matching MetadataValue object in a map, or `undefined`. */
+  public static first(mdMapOrMaps: MetadataMap | MetadataMap[], keyOrKeys: string | string[],
+                      filter?: MetadataValueFilter): MetadataValue {
+    const mdMaps: MetadataMap[] = mdMapOrMaps instanceof Array ? mdMapOrMaps : [ mdMapOrMaps ];
+    for (const mdMap of mdMaps) {
+      for (const key of Metadata.resolveKeys(mdMap, keyOrKeys)) {
+        const values: MetadataValue[] = mdMap[key];
+        if (values) {
+          return values.find((value: MetadataValue) => Metadata.valueMatches(value, filter));
+        }
+      }
+    }
+  }
+
+  /** Like `first`, but only returns a string value, or `undefined`. */
+  public static firstValue(mdMapOrMaps: MetadataMap | MetadataMap[], keyOrKeys: string | string[],
+                           filter?: MetadataValueFilter): string {
+    const value = Metadata.first(mdMapOrMaps, keyOrKeys, filter);
+    return value === undefined ? undefined : value.value;
+  }
+
+  /** Checks the given map for a matching value. */
+  public static has(mdMapOrMaps: MetadataMap | MetadataMap[], keyOrKeys: string | string[],
+                    filter?: MetadataValueFilter): boolean {
+    return Metadata.first(mdMapOrMaps, keyOrKeys, filter) !== undefined;
+  }
+
+  /** Checks if a value matches a filter. */
+  public static valueMatches(mdValue: MetadataValue, filter: MetadataValueFilter) {
+    if (!filter) {
+      return true;
+    } else if (filter.language && filter.language !== mdValue.language) {
+      return false;
+    } else if (filter.value) {
+      let fValue = filter.value;
+      let mValue = mdValue.value;
+      if (filter.ignoreCase) {
+        fValue = filter.value.toLowerCase();
+        mValue = mdValue.value.toLowerCase();
+      }
+      if (filter.substring) {
+        return mValue.includes(fValue);
+      } else {
+        return mValue === fValue;
+      }
+    }
+    return true;
+  }
+
+  /** Gets the list of keys in the map limited by, and in the order given by `keyOrKeys` */
+  private static resolveKeys(mdMap: MetadataMap, keyOrKeys: string | string[]): string[] {
+    const inputKeys: string[] = keyOrKeys instanceof Array ? keyOrKeys : [ keyOrKeys ];
+    const outputKeys: string[] = [];
+    for (const inputKey of inputKeys) {
+      if (inputKey.includes('*')) {
+        const inputKeyRegex = new RegExp('^' + inputKey.replace('.', '\.').replace('*', '.*') + '$');
+        for (const mapKey of Object.keys(mdMap)) {
+          if (!outputKeys.includes(mapKey) && inputKeyRegex.test(mapKey)) {
+            outputKeys.push(mapKey);
+          }
+        }
+      } else if (mdMap.hasOwnProperty(inputKey) && !outputKeys.includes(inputKey)) {
+        outputKeys.push(inputKey);
+      }
+    }
+    return outputKeys;
+  }
+}

src/app/core/shared/metadatum.model.ts

@@ -1,23 +0,0 @@
-import { autoserialize } from 'cerialize';
-
-export class Metadatum {
-
-  /**
-   * The metadata field of this Metadatum
-   */
-  @autoserialize
-  key: string;
-
-  /**
-   * The language of this Metadatum
-   */
-  @autoserialize
-  language: string;
-
-  /**
-   * The value of this Metadatum
-   */
-  @autoserialize
-  value: string;
-
-}

src/app/shared/comcol-forms/comcol-form/comcol-form.component.ts

@@ -8,6 +8,7 @@ import { FormGroup } from '@angular/forms';
 import { DynamicFormControlModel } from '@ng-dynamic-forms/core/src/model/dynamic-form-control.model';
 import { TranslateService } from '@ngx-translate/core';
 import { DSpaceObject } from '../../../core/shared/dspace-object.model';
+import { MetadataMap, MetadataValue } from '../../../core/shared/metadata.interfaces';
 import { isNotEmpty } from '../../empty.util';
 import { ResourceType } from '../../../core/shared/resource-type';
 
@@ -64,7 +65,7 @@ export class ComColFormComponent<T extends DSpaceObject> implements OnInit {
   ngOnInit(): void {
     this.formModel.forEach(
       (fieldModel: DynamicInputModel) => {
-        fieldModel.value = this.dso.findMetadata(fieldModel.name);
+        fieldModel.value = this.dso.firstMetadataValue(fieldModel.name);
       }
     );
     this.formGroup = this.formService.createFormGroup(this.formModel);
@@ -77,20 +78,24 @@ export class ComColFormComponent<T extends DSpaceObject> implements OnInit {
   }
 
   /**
-   * Checks which new fields where added and sends the updated version of the DSO to the parent component
+   * Checks which new fields were added and sends the updated version of the DSO to the parent component
    */
   onSubmit() {
-    const metadata = this.formModel.map(
+    const formMetadata = new Object() as MetadataMap;
-      (fieldModel: DynamicInputModel) => {
+    this.formModel.forEach((fieldModel: DynamicInputModel) => {
-        return { key: fieldModel.name, value: fieldModel.value }
+      const value: MetadataValue = { value: fieldModel.value as string, language: null };
+      if (formMetadata.hasOwnProperty(fieldModel.name)) {
+        formMetadata[fieldModel.name].push(value);
+      } else {
+        formMetadata[fieldModel.name] = [ value ];
       }
-    );
+    });
-    const filteredOldMetadata = this.dso.metadata.filter((filter) => !metadata.map((md) => md.key).includes(filter.key));
-    const filteredNewMetadata = metadata.filter((md) => isNotEmpty(md.value));
 
-    const newMetadata = [...filteredOldMetadata, ...filteredNewMetadata];
     const updatedDSO = Object.assign({}, this.dso, {
-      metadata: newMetadata,
+      metadata: {
+        ...this.dso.metadata,
+        ...formMetadata
+      },
       type: ResourceType.Community
     });
     this.submitForm.emit(updatedDSO);

src/app/shared/object-collection/shared/object-collection-element/abstract-listable-element.component.ts

@@ -1,6 +1,5 @@
 import { Component, Inject } from '@angular/core';
 import { ListableObject } from '../listable-object.model';
-import { hasValue } from '../../../empty.util';
 
 @Component({
   selector: 'ds-abstract-object-element',
@@ -11,8 +10,4 @@ export class AbstractListableElementComponent <T extends ListableObject> {
   public constructor(@Inject('objectElementProvider') public listableObject: ListableObject) {
     this.object = listableObject as T;
   }
-
-  hasValue(data) {
-    return hasValue(data);
-  }
 }

src/app/shared/object-grid/item-grid-element/item-grid-element.component.html

@@ -5,19 +5,19 @@
       </ds-grid-thumbnail>
     </a>
     <div class="card-body">
-      <h4 class="card-title">{{object.findMetadata('dc.title')}}</h4>
+      <h4 class="card-title">{{object.firstMetadataValue('dc.title')}}</h4>
 
       <ds-truncatable-part [id]="object.id" [minLines]="2">
-        <p *ngIf="object.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']).length > 0" class="item-authors card-text text-muted">
+        <p *ngIf="object.hasMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*'])" class="item-authors card-text text-muted">
-            <span *ngFor="let authorMd of object.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">{{authorMd.value}}
+            <span *ngFor="let author of object.allMetadataValues(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">{{author}}
                 <span *ngIf="!last">; </span>
             </span>
-          <span *ngIf="hasValue(object.findMetadata('dc.date.issued'))" class="item-date">{{object.findMetadata("dc.date.issued")}}</span>
+          <span *ngIf="object.hasMetadata('dc.date.issued')" class="item-date">{{object.firstMetadataValue("dc.date.issued")}}</span>
         </p>
       </ds-truncatable-part>
 
       <ds-truncatable-part [id]="object.id" [minLines]="5">
-        <p *ngIf="object.findMetadata('dc.description.abstract')" class="item-abstract card-text">{{object.findMetadata("dc.description.abstract") }}</p>
+        <p *ngIf="object.hasMetadata('dc.description.abstract')" class="item-abstract card-text">{{object.firstMetadataValue("dc.description.abstract")}}</p>
       </ds-truncatable-part>
 
       <div class="text-center pt-2">

src/app/shared/object-grid/search-result-grid-element/item-search-result/item-search-result-grid-element.component.html

@@ -8,20 +8,20 @@
         </a>
         <div class="card-body">
             <ds-truncatable-part [fixedHeight]="true" [id]="dso.id" [minLines]="3" type="h4">
-                <h4 class="card-title" [innerHTML]="dso.findMetadata('dc.title')"></h4>
+                <h4 class="card-title" [innerHTML]="dso.firstMetadataValue('dc.title')"></h4>
             </ds-truncatable-part>
-            <p *ngIf="dso.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']).length > 0"
+            <p *ngIf="dso.hasMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*'])"
                class="item-authors card-text text-muted">
                 <ds-truncatable-part [fixedHeight]="true" [id]="dso.id" [minLines]="1">
-                    <span *ngIf="hasValue(dso.findMetadata('dc.date.issued'))" class="item-date">{{dso.findMetadata("dc.date.issued")}}</span>
+                    <span *ngIf="dso.hasMetadata('dc.date.issued')" class="item-date">{{dso.firstMetadataValue('dc.date.issued')}}</span>
-                    <span *ngFor="let authorMd of dso.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']);">,
+                    <span *ngFor="let author of dso.allMetadataValues(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']);">,
-                        <span [innerHTML]="authorMd.value"></span>
+                        <span [innerHTML]="author"></span>
                     </span>
                 </ds-truncatable-part>
             </p>
             <p class="item-abstract card-text">
                 <ds-truncatable-part [fixedHeight]="true" [id]="dso.id" [minLines]="3">
-                    <span [innerHTML]="getFirstValue('dc.description.abstract')"></span>
+                    <span [innerHTML]="firstMetadataValue('dc.description.abstract')"></span>
                 </ds-truncatable-part>
             </p>
             <div class="text-center">

src/app/shared/object-grid/search-result-grid-element/search-result-grid-element.component.ts

@@ -2,12 +2,11 @@ import { Component, Inject } from '@angular/core';
 
 import { SearchResult } from '../../../+search-page/search-result.model';
 import { DSpaceObject } from '../../../core/shared/dspace-object.model';
-import { Metadatum } from '../../../core/shared/metadatum.model';
-import { isEmpty, hasNoValue, hasValue } from '../../empty.util';
 import { AbstractListableElementComponent } from '../../object-collection/shared/object-collection-element/abstract-listable-element.component';
 import { ListableObject } from '../../object-collection/shared/listable-object.model';
 import { TruncatableService } from '../../truncatable/truncatable.service';
 import { Observable } from 'rxjs';
+import { Metadata } from '../../../core/shared/metadata.model';
 
 @Component({
   selector: 'ds-search-result-grid-element',
@@ -22,39 +21,14 @@ export class SearchResultGridElementComponent<T extends SearchResult<K>, K exten
     this.dso = this.object.dspaceObject;
   }
 
-  getValues(keys: string[]): string[] {
+  /** Gets all matching metadata string values from hitHighlights or dso metadata, preferring hitHighlights. */
-    const results: string[] = new Array<string>();
+  allMetadataValues(keyOrKeys: string | string[]): string[] {
-    this.object.hitHighlights.forEach(
+    return Metadata.allValues([this.object.hitHighlights, this.dso.metadata], keyOrKeys);
-      (md: Metadatum) => {
-        if (keys.indexOf(md.key) > -1) {
-          results.push(md.value);
-        }
-      }
-    );
-    if (isEmpty(results)) {
-      this.dso.filterMetadata(keys).forEach(
-        (md: Metadatum) => {
-          results.push(md.value);
-        }
-      );
-    }
-    return results;
   }
 
-  getFirstValue(key: string): string {
+  /** Gets the first matching metadata string value from hitHighlights or dso metadata, preferring hitHighlights. */
-    let result: string;
+  firstMetadataValue(keyOrKeys: string | string[]): string {
-    this.object.hitHighlights.some(
+    return Metadata.firstValue([this.object.hitHighlights, this.dso.metadata], keyOrKeys);
-      (md: Metadatum) => {
-        if (key === md.key) {
-          result = md.value;
-          return true;
-        }
-      }
-    );
-    if (hasNoValue(result)) {
-      result = this.dso.findMetadata(key);
-    }
-    return result;
   }
 
   isCollapsed(): Observable<boolean> {

src/app/shared/object-list/item-list-element/item-list-element.component.html

@@ -1,23 +1,23 @@
 <ds-truncatable [id]="object.id">
   <a [routerLink]="['/items/' + object.id]" class="lead">
-      {{object.findMetadata("dc.title")}}
+    {{object.firstMetadataValue("dc.title")}}
   </a>
   <div>
     <ds-truncatable-part [id]="object.id" [minLines]="1">
       <span class="text-muted">
-        <span *ngIf="object.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']).length > 0"
+        <span *ngIf="object.hasMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*'])"
               class="item-list-authors">
-            <span *ngFor="let authorMd of object.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">{{authorMd.value}}
+            <span *ngFor="let author of object.allMetadataValues(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">{{author}}
                 <span *ngIf="!last">; </span>
             </span>
         </span>
-        (<span *ngIf="hasValue(object.findMetadata('dc.publisher'))" class="item-list-publisher">{{object.findMetadata("dc.publisher")}}, </span><span
+        (<span *ngIf="object.hasMetadata('dc.publisher')" class="item-list-publisher">{{object.firstMetadataValue("dc.publisher")}}, </span><span
-              *ngIf="hasValue(object.findMetadata('dc.date.issued'))" class="item-list-date">{{object.findMetadata("dc.date.issued")}}</span>)
+        *ngIf="object.hasMetadata('dc.date.issued')" class="item-list-date">{{object.firstMetadataValue("dc.date.issued")}}</span>)
       </span>
     </ds-truncatable-part>
     <ds-truncatable-part [id]="object.id" [minLines]="3">
-      <div *ngIf="object.findMetadata('dc.description.abstract')" class="item-list-abstract">
+      <div *ngIf="object.hasMetadata('dc.description.abstract')" class="item-list-abstract">
-          {{object.findMetadata("dc.description.abstract")}}
+        {{object.firstMetadataValue("dc.description.abstract")}}
       </div>
     </ds-truncatable-part>
   </div>

src/app/shared/object-list/search-result-list-element/collection-search-result/collection-search-result-list-element.component.html

@@ -1,2 +1,2 @@
-<a [routerLink]="['/collections/' + dso.id]" class="lead" [innerHTML]="getFirstValue('dc.title')"></a>
+<a [routerLink]="['/collections/' + dso.id]" class="lead" [innerHTML]="firstMetadataValue('dc.title')"></a>
-<div *ngIf="dso.shortDescription" class="text-muted abstract-text" [innerHTML]="getFirstValue('dc.description.abstract')"></div>
+<div *ngIf="dso.shortDescription" class="text-muted abstract-text" [innerHTML]="firstMetadataValue('dc.description.abstract')"></div>

src/app/shared/object-list/search-result-list-element/community-search-result/community-search-result-list-element.component.html

@@ -1,2 +1,2 @@
-<a [routerLink]="['/communities/' + dso.id]" class="lead" [innerHTML]="getFirstValue('dc.title')"></a>
+<a [routerLink]="['/communities/' + dso.id]" class="lead" [innerHTML]="firstMetadataValue('dc.title')"></a>
-<div *ngIf="dso.shortDescription" class="text-muted abstract-text" [innerHTML]="getFirstValue('dc.description.abstract')"></div>
+<div *ngIf="dso.shortDescription" class="text-muted abstract-text" [innerHTML]="firstMetadataValue('dc.description.abstract')"></div>

src/app/shared/object-list/search-result-list-element/item-search-result/item-search-result-list-element.component.html

@@ -1,24 +1,24 @@
 <ds-truncatable [id]="dso.id">
         <a
             [routerLink]="['/items/' + dso.id]" class="lead"
-            [innerHTML]="getFirstValue('dc.title')"></a>
+            [innerHTML]="firstMetadataValue('dc.title')"></a>
   <span class="text-muted">
     <ds-truncatable-part [id]="dso.id" [minLines]="1">
-            (<span *ngIf="dso.findMetadata('dc.publisher')" class="item-list-publisher"
+            (<span *ngIf="dso.hasMetadata('dc.publisher')" class="item-list-publisher"
-                   [innerHTML]="getFirstValue('dc.publisher') + ', '"></span><span
+                   [innerHTML]="firstMetadataValue('dc.publisher') + ', '"></span><span
-            *ngIf="hasValue(dso.findMetadata('dc.date.issued'))" class="item-list-date"
+      *ngIf="dso.hasMetadata('dc.date.issued')" class="item-list-date"
-            [innerHTML]="getFirstValue('dc.date.issued')"></span>)
+      [innerHTML]="firstMetadataValue('dc.date.issued')"></span>)
-            <span *ngIf="dso.filterMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']).length > 0"
+            <span *ngIf="dso.hasMetadata(['dc.contributor.author', 'dc.creator', 'dc.contributor.*'])"
                   class="item-list-authors">
-                    <span *ngFor="let author of getValues(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">
+                    <span *ngFor="let author of allMetadataValues(['dc.contributor.author', 'dc.creator', 'dc.contributor.*']); let last=last;">
                         <span [innerHTML]="author"><span [innerHTML]="author"></span></span>
                     </span>
             </span>
         </ds-truncatable-part>
   </span>
-            <div *ngIf="dso.findMetadata('dc.description.abstract')" class="item-list-abstract">
+            <div *ngIf="dso.hasMetadata('dc.description.abstract')" class="item-list-abstract">
                 <ds-truncatable-part [id]="dso.id" [minLines]="3"><span
-                        [innerHTML]="getFirstValue('dc.description.abstract')"></span>
+                        [innerHTML]="firstMetadataValue('dc.description.abstract')"></span>
                 </ds-truncatable-part>
             </div>
 </ds-truncatable>

src/app/shared/object-list/search-result-list-element/search-result-list-element.component.ts

@@ -3,11 +3,10 @@ import { Observable } from 'rxjs';
 
 import { SearchResult } from '../../../+search-page/search-result.model';
 import { DSpaceObject } from '../../../core/shared/dspace-object.model';
-import { Metadatum } from '../../../core/shared/metadatum.model';
-import { hasNoValue, isEmpty } from '../../empty.util';
 import { ListableObject } from '../../object-collection/shared/listable-object.model';
 import { AbstractListableElementComponent } from '../../object-collection/shared/object-collection-element/abstract-listable-element.component';
 import { TruncatableService } from '../../truncatable/truncatable.service';
+import { Metadata } from '../../../core/shared/metadata.model';
 
 @Component({
   selector: 'ds-search-result-list-element',
@@ -22,39 +21,14 @@ export class SearchResultListElementComponent<T extends SearchResult<K>, K exten
     this.dso = this.object.dspaceObject;
   }
 
-  getValues(keys: string[]): string[] {
+  /** Gets all matching metadata string values from hitHighlights or dso metadata, preferring hitHighlights. */
-    const results: string[] = new Array<string>();
+  allMetadataValues(keyOrKeys: string | string[]): string[] {
-    this.object.hitHighlights.forEach(
+    return Metadata.allValues([this.object.hitHighlights, this.dso.metadata], keyOrKeys);
-      (md: Metadatum) => {
-        if (keys.indexOf(md.key) > -1) {
-          results.push(md.value);
-        }
-      }
-    );
-    if (isEmpty(results)) {
-      this.dso.filterMetadata(keys).forEach(
-        (md: Metadatum) => {
-          results.push(md.value);
-        }
-      );
-    }
-    return results;
   }
 
-  getFirstValue(key: string): string {
+  /** Gets the first matching metadata string value from hitHighlights or dso metadata, preferring hitHighlights. */
-    let result: string;
+  firstMetadataValue(keyOrKeys: string | string[]): string {
-    this.object.hitHighlights.some(
+    return Metadata.firstValue([this.object.hitHighlights, this.dso.metadata], keyOrKeys);
-      (md: Metadatum) => {
-        if (key === md.key) {
-          result = md.value;
-          return true;
-        }
-      }
-    );
-    if (hasNoValue(result)) {
-      result = this.dso.findMetadata(key);
-    }
-    return result;
   }
 
   isCollapsed(): Observable<boolean> {